Transcriptomic Insights into the Life History of Bolidophytes, the Sister Lineage to Diatoms. Issue 6 (3rd September 2014)

• Record Type: Journal Article
• Authors: Kessenich, Colton R.; Ruck, Elizabeth C.; Schurko, Andrew M.; Wickett, Norman J.; Alverson, Andrew J.; De Clerck, O.
• Is Part Of: Journal of phycology. Volume 50:Issue 6(2014:Dec.)
• Page Start: 977
• Page End: 983
• Publication Date: 2014-09-03
• Subjects: Algae -- Periodicals; 579.8
• DOI: 10.1111/jpy.12222
• Languages: English
• ISSNs: 0022-3646

Abstract

<abstract abstract-type="main" id="jpy12222-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Diatoms are perhaps the most diverse lineage of eukaryotic algae, with their siliceous cell wall and diplontic life history often considered to have played important roles in their extraordinary diversification. The characteristic diminution of the diatom cell wall over the course of vegetative growth provides a reliable, intrinsic trigger for sexual reproduction, establishing a direct link between the evolution of their cell‐wall and life‐history features. It is unclear, however, whether the diplontic life cycle of diatoms represents an ancestral or derived trait. This uncertainty is based in part on our lack of understanding of the life cycle of the sister lineage to diatoms, which includes a mix of two free‐living and separately classified forms: naked biflagellate unicells in the genus <italic>Bolidomonas</italic> and silicified forms in the order Parmales. These two forms might represent different life‐history stages, although directly establishing such links can be difficult. We sequenced transcriptomes for <italic>Bolidomonas</italic> and two diatoms and found that ~0.1% of the coding regions in the two diploid diatoms are heterozygous, whereas <italic>Bolidomonas</italic> is virtually devoid of heterozygous alleles, consistent with expectations for a haploid genome. These results suggest that <italic>Bolidomonas</italic> is haploid and predict that parmaleans represent the diploid phase of a haplodiplontic life cycle. These data fill an important gap in our understanding of the origin of the diplontic life history of diatoms, which may represent an evolutionarily derived, adaptive feature.</p> </abstract>